Some 45,000 years ago

Dec 16, 2006 10:18 GMT  ·  By

Well, it seems that African Blacks are just ... migrants to Africa! ...

DNA analysis from ancient human fossils found in Africa suggests that, after the initial escape out of Africa about 70,000 years ago, the some human populations returned to the Black Continent, 30,000 years later coming from Middle East.

The return to Africa occurred around the same time the modern humans, from a stock also in the Middle East, entered the - till then - Neanderthal-territory Europe (the so-called Cro-Magnon people (a skull photo), which had indeed African Negroid features). "We were rather surprised by the age of the migration back to Africa," said Antonio Torroni, a geneticist at the University of Pavia in Italy. "We did not really expect that it was 40,000 to 45,000 years old."

"But the age and the fact that the migration had originated in the Levant (the region at the east of Mediterranean Sea) led us to link the migration to Africa to that occurring at the same time toward Europe from the same region," added Torroni.

The new study builds on the theory that humans migrated from Africa in a single dispersal about 70,000 years ago. The most widely accepted hypothesis is that humans left for the first time Africa 70,000 years ago by crossing the Red Sea area, then followed a coastal route along the Arabian Peninsula and on to India, Southeast Asia, Indonesia, and Australia. The single "out of Africa" dispersal seems to have given rise to all modern non-African populations.

But researchers noticed that two genetic populations found in northern and eastern Africa appear to have Asian ancestors. The scientists sequenced the mitochondrial DNA, which is passed only from mother to daughter, from 81 individuals in both of these genetic groups, finding that the two populations must have arisen in southwestern Asia and returned to Africa about 40,000 to 45,000 years ago.

But these populations did not follow the previous southern coastal route. The researchers believe that before reaching the Levant, migrating humans may have stopped at the Persian Gulf for some time because of a hostile climate. Migrating to north Africa from southwestern Asia would have been impossible earlier than 50,000 years ago, as a vast desert extended from northern Africa to central Asia. "When weather conditions improved, the desert was fragmented and reduced in size," said Anna Olivieri, a geneticist in the research team. "The human groups living in the coastal regions of southwestern Asia were able to move inland."

"Some of them colonized first the Levant and from there all surrounding regions including Europe and North Africa," she said. "Consider also that the Sahara desert in North Africa was reducing its size. Thus, that region became interesting from a human colonization perspective."

These 45,000 years old migration might have originated the African Negroid types (typical African Blacks). Older African races are Khoisan (bushmen), Nilotic (Masai-Nuba type), and Pygmies.